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GENERAL
FUEL, COOLANT, AND LUBRICANTS
12
COOLANT SPECIFICATIONS
GENERAL
Selection and maintenance of the engine coolant is important to long engine life. The following information provides recom-
mendations for selecting the engine coolant and maintaining the coolant inhibitors.
Heavy duty diesel engines require a balanced coolant mixture of water, antifreeze, and supplemental coolant additives. Supple-
mental coolant additive recommendations are included in the section entitled "Inhibitors/Conditioners." The coolant mixture
must be drained and replaced at the specified service interval shown in the maintenance schedule chart, or every two years of
operation, whichever comes first.
WATER
Use water which has a low mineral content. Water used in conjunction with antifreeze, coolant filters and inhibited water must
meet the following standards:
Total Hardness:
Not to exceed 170 parts per million (10 grains/gallon maximum) to prevent scale deposits. Water containing dissolved magne-
sium and calcium (the usual reason for water hardness) above the specified amount will cause scale deposits to develop in the
engine.
Chlorides:
Not to exceed 40 parts per million (2.5 grains/gallon maximum) to prevent corrosion.
Sulfates:
Not to exceed 100 parts per million (5.8 grains/gallon maximum) to prevent corrosion.
Dissolved Solids:
Not to exceed 340 parts per million (20 grains/gallon maximum) to minimize sludge deposits, scale deposits, corrosion or a
combination of these.
If any of the above requirements cannot be met, use distilled, de-ionized, or de-mineralized water. To determine if local water
supplies meet these standards, water samples can be tested by water treatment laboratories. "Softened" water that is prepared
using common salt (sodium chloride) contains excessive amounts of chlorides and should not be used.
Never use water alone in the cooling system because corrosion will occur.
ANTIFREEZE
In climates where the temperature is above -37° C (-34° F), use a coolant mixture that contains 50 percent antifreeze. Anti-
freeze is essential in any climate. It broadens the operating temperature range by lowering the coolant freezing point and by
raising its boiling point. Do not use more than 50 percent antifreeze in the mixture unless additional freeze protection is
required. Never use more than 68 percent antifreeze under any condition.
An antifreeze concentration greater than 68% will adversely affect freeze protection and heat transfer rates. Antifreeze concen-
trations between 68 and 100% actually have a higher freezing point than a 68% antifreeze concentration and should not be
used due to reduced heat transfer rates.
Low silicate ethylene glycol antifreeze is recommended. The antifreeze should contain no more than 0.1% anhydrous alkali
metasilicate. Low silicate antifreeze is recommended to avoid the formation of silica-gel (hydro-gel). This gel formation can
occur when the cooling system contains an over concentration of high silicate antifreeze and/or supplemental coolant additive.
DO NOT use methanol or alcohol as an antifreeze because of its low boiling point.
GD530/650/670
01-7
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